There are different dental filling materials which are used for restorative purposes, including amalgam and dental composite materials. In order to fulfill its function (replacement of lost tooth structure), dental filling materials need to have adequate physical properties. In particular, they have to have sufficient strength to be able to absorb and resist chewing forces. If, however, the material is too hard, it will also become more brittle. Thus, a dental filling material not only needs to be sufficiently hard, but also needs to be to some extend flexible.
To address these needs, commercially available dental composite filling materials typically contain a certain amounts of resin matrix, filler and initiator.
A widely used polymerizable (meth)acrylate component contained in the resin matrix is bisphenol A-glycidyl methacrylate (Bis-GMA) or other bisphenol based (meth)acrylate monomers.
Compositions containing bisphenol-based monomers are said to have a variety of advantageous properties like high compressive strength, thus enabling the practitioner to formulate a variety of different dental compositions for restorative purposes.
Some literature, however, seems to indicate that bisphenol based monomers are not always recommended for all purposes. Alternative polymerizable (meth)acrylate components are thus needed.
US 2010/076115 (Heraeus Kulzer) relates to compositions for dental composites comprising acrylic acid esters of tricyclo[5.2.1.02.6] decane with urethane groups
U.S. Pat. No. 3,853,962 (Gander) relates to dental restorative cements comprising the methacrylate monomer 1,3-bis[2-,3-di(methacryloxy)-propoxy]-benzene. Restorative compositions containing this kind of monomer are said to have improved compressive strength and related physical properties.
U.S. Pat. No. 4,744,827 (Winkel) describes (meth)acrylic acid derivatives of a tricyclodecane exhibiting considerably less polymerization shrinkage.
WO 2012/003136 (3M) relates to a dental composition comprising a hardenable compound with a comparable rigid backbone, which may comprise urethane moieties. The composition is said to have advantageous properties e.g. with respect to shrinkage stress.
WO 2009/042574 (3M) describes methacrylate based monomers containing a urethane linkage showing a well balanced properties with respect to viscosity, refractive index, molecular weight and shrinkage value.
US 2011/0315928 (Jin et al.) describes a low stress flowable dental composition comprising an oligomeric resin, a second resin and a filler. The composition is said to be self-leveling and be suitable as bulk fill material. The oligomeric resin contains a photoresponsive moiety which may be derived from any conventional initiator.